Multi-curvature liners for reversed shoulder replacement

ABSTRACT

A reverse shoulder replacement system including a humeral liner defining a split curvature bearing surface that includes a plurality of curvature regions. The plurality of curvature regions are configured to engage a glenosphere of a glenoid implant individually or in combination to provide an improved fit between the glenosphere and the humeral liner.

CLAIM OF PRIORITY

This patent application is a divisional of U.S. patent application Ser.No. 15/367,881, filed on Dec. 2, 2016, which claims the benefit ofpriority, under 35 U.S.C. Section 119(e), to Andrew Hopkins, U.S. PatentApplication Ser. No. 62/262,415, entitled “MULTI-CURVATURE LINERS FORREVERSED SHOULDER REPLACEMENT,” filed on Dec. 3, 2015, which is herebyincorporated by reference herein in its entirety.

TECHNICAL FIELD

The document pertains generally, but not by way of limitation, tosystems and related methods for reversed shoulder replacementprocedures.

BACKGROUND

The shoulder joint is formed by the ball-shaped humeral head of thehumerus rotatably being received within the glenoid cavity of thescapula. A group of tendons and muscles at the rotator cuff extendbetween the scapula and the humerus to maintain the humeral head withinthe glenoid cavity. Disease and overuse can cause the rotator cuffmuscles and tendons to become damaged, weakening the connection betweenthe humeral head and the glenoid cavity and permitting the humeral headto shift or track unnaturally within the glenoid cavity. The irregularmovement of the humeral head can damage the humeral head or the scapula,requiring repair or replacement of the humeral head or the bonesurrounding the glenoid cavity.

In conventional shoulder replacement procedures, a humeral implanthaving a ball head and/or a glenoid implant defining a socket aremounted to the humerus and scapula, respectively. The conventionalhumeral and glenoid implants are intended to supplement or replace theexisting bone structure damaged by the irregular movement of the humeralhead. As the conventional implants are substitutes for the naturalstructures, conventional shoulder replacement procedures require therotator cuff muscles and tendons to be sufficiently undamaged or healedto maintain proper contact between the humeral head and glenoid cavityand prevent irregular movement of the humeral head.

A reverse shoulder replacement procedure can be employed if the rotatorcuff muscles and tendons are too damaged for a conventional procedure.In reverse shoulder replacement, a glenoid implant having a ball head,or glenosphere, can be mounted to the scapula and a humeral implantdefining a socket is mounted to the humerus. The glenoid and humeralimplants reverse the ball and socket of the natural shoulder joint suchthat the deltoid muscle, rather than the damaged rotator cuff musclesand tendons, can be used to maintain the joining of the humerus andscapular.

OVERVIEW

The present inventors have recognized, among other things, that aproblem to be solved can include that in modular reverse shouldersystems, the glenosphere of the selected glenoid implant must becorrectly matched with the humeral implant defining a socket of theappropriate curvature. As reverse shoulder replacement proceduresreverse the normal orientation of the shoulder, the fit of theglenosphere of the glenoid implant to the socket defined by the humeralimplant can significantly impact the resulting joint tension. Reverseshoulder implant systems can be modular systems including a plurality ofglenospheres of different diameters and a plurality of different humeralimplants each including a socket of a different curvature to assistsurgeons in providing the proper fit. Surgeons select the appropriateglenosphere diameter based on the dimensions of the scapula, theorientation of the glenoid cavity, the desired joint angle, and otherfactors. Surgeons then select the appropriate curvature of the socketdefined by the humeral implant that corresponds to the diameter of theglenosphere and other physical constraints of the reversed joint.

However, if the surgeon incorrectly selects the glenoid cavity curvatureor glenosphere diameter, the joint contact can be insufficiently tightcausing excessive wear of the joint and/or damage to the joint therebyrequiring revision surgery. In an example, the present subject mattercan provide a solution to this problem, such as providing a humeralimplant configured to receive a humeral liner defining a split curvaturebearing surface. The split curvature bearing surface can include two ormore curvature regions, each curvature region having a differentcurvature for engaging a glenosphere of a glenoid implant. The differentcurvature region can permit a single humeral implant to interface withglenospheres of different diameters and can account for different jointangles. This arrangement can reduce the likelihood of a mismatch betweenthe humeral implant and the selected glenoid implant thereby reducing alikelihood that revision surgery will be required. The split curvaturealso can account for slight mismatches between the curvature regions ofthe humeral liner and the glenosphere by providing a series of regionsof different curvatures reducing the potential differences betweencurvature and glenosphere diameters. This arrangement can also helpreduce the complexity and cost of the implant procedure as only multipleglenoid implants need be provided for selection instead of providingboth multiple humeral implants and glenoid implants.

In an example, the curvature regions of the split curvature bearingsurface can be configured to facilitate wearing in or “bedding” of thesplit curvature bearing surface by the glenosphere through repeated useof the assembled joint. In at least one example, the flatter curvatureregions can be positioned proximate the center of the split curvaturebearing surface while the steeper curvature regions can be positionedproximate the edges of the split curvature bearing surface. The wearingin of the split curvature bearing surface can erode a portion of theslightly mismatched curvature regions and/or the interface betweencurvature regions such as to improve the fit of the glenosphere to thehumeral liner thereby providing flexibility in the selection of thehumeral liner. The split curvature bearing surface can be configured todeflect or deform to conform the split curvature bearing surface to theglenosphere. The wearing-in of the split-curvature bearing surface canimprove the fit of the humeral implant to the selected glenoid implant.In at least one example, the humeral liner can comprise a deformablebiocompatible material, such as polyethylene, which can facilitate wearor deflection of the split curvature bearing surface such as tocorrespond to the glenosphere over time.

A reverse shoulder replacement system, according to an example of thepresent disclosure, can include a humeral liner defining a splitcurvature bearing surface. The split curvature bearing surface caninclude a plurality of curvature regions, such as can include at least afirst curvature region having a first curvature, and a second curvatureregion having a second curvature. The first curvature can be defined bya first radius extending from a first focal point, while the secondcurvature can be defined by a second radius extending from a secondfocal point. In an example, the first radius is shorter than the secondradius such that the second curvature is shallower than the firstcurvature. In at least one example, the humeral liner can comprise abiocompatible deformable material, such as polyethylene.

A method for reverse shoulder replacement, according to an example ofthe present disclosure can include inserting a stem of a humeral implantinto a humerus and mounting a humeral liner to an end of the stem. Thehumeral liner can define a split curvature bearing surface including aplurality of curvature regions including at least a first curvatureregion having a first curvature and a second curvature region having asecond curvature, which can be different than the first curvature. Themethod can also include mounting a glenoid implant including aglenosphere to a glenoid region of a scapula and positioning the humeralimplant such that at least one of the curvature regions operably engagesthe glenosphere of the glenoid implant.

In at least one example, the method can also include resecting at leasta portion of the humerus to provide a humeral mounting surface forreceiving the humeral implant, and resecting at least a portion of thescapula to provide a glenoid mounting surface for receiving the glenoidimplant. The method can also include positioning a spacer between thehumeral liner and the humeral stem.

This overview is intended to provide an overview of subject matter ofthe present patent application. It is not intended to provide anexclusive or exhaustive explanation of the present subject matter. Thedetailed description is included to provide further information aboutthe present patent application.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. Like numerals havingdifferent letter suffixes may represent different instances of similarcomponents. The drawings illustrate generally, by way of example, butnot by way of limitation, various embodiments discussed in the presentdocument.

FIG. 1 is an exploded view of a reverse shoulder implant systemaccording to an example of the present disclosure.

FIG. 2 is a schematic diagram of a humeral liner according to an exampleof the present disclosure.

FIG. 3 is a schematic diagram of the humeral liner depicted in FIG. 2interfacing with a glenosphere having a diameter corresponding to afirst curvature region of the humeral liner.

FIG. 4 is a schematic diagram of the humeral liner depicted in FIG. 2interfacing with a glenosphere having a diameter corresponding to asecond curvature region of the humeral liner.

DETAILED DESCRIPTION

As depicted in FIG. 1, a reverse shoulder implant system 10, accordingto at least one example of the present disclosure, can include a humeralimplant 12, a glenoid implant 14 and a humeral liner 16. The humeralimplant 12 can be mounted to a humerus, and the glenoid implant 14 canbe mounted to the scapula at the glenoid cavity. The humeral liner 16can be positioned on the humeral implant 12, such as to provide aninterface between the humeral implant 12 and the glenoid implant 14. Inat least one example, a spacer 18 can be positioned between the humeralimplant 12 and the humeral liner 16, such as to change the axialpositioning of the humeral liner 16 on the humeral implant 12.

The humeral implant 12 can include an attachment head 20 and a humeralstem 22. The attachment head 20 can define a planar surface 24 and canbe configured to operably engage the humeral liner 16 or the spacer 18such that the humeral liner 16 or the spacer 18 is positioned againstthe planar surface 24. In at least one example, the attachment head 20can include a port 26, such as for receiving a shank of the humeralliner 16 or the spacer 18, such as to couple the humeral liner 16 or thespacer 18 to the attachment head 20. As depicted in FIG. 1, theattachment head 20, such as to couple to the spacer 18 or the humeralliner 16, such as with a Morse taper type coupling, but the attachmenthead 20 can also be configured to be coupled through a screw-inconfiguration, a flexible tab or detent configuration, or one or moreother mechanical coupling arrangements.

The glenoid implant 14 can include a glenosphere 28 and a base plate 30.The glenosphere 28 can comprise an exterior face 32 having ahemispherical shape. In at least one example, the curved exterior face32 of the glenosphere 28 can have a diameter between about 34 mm toabout 46 mm. The base plate 30 can be attached to the glenosphere 28,such as opposite the exterior face 32 of the glenosphere 28. In at leastone example, the glenosphere 28 can include a shank, such as can beengaged to a corresponding port defined by the base plate 30. The baseplate 30 can be attached to the glenosphere 28 such as through a Morsetaper configuration, a screw-in configuration, a flexible tab or detentconfiguration, or one or more another mechanical arrangement. In atleast one example, the glenosphere 28 can be integral to the base plate30. The base plate 30 can be configured to receive at least one lockingscrew 34, such as for mounting the base plate 30 to the scapula. In atleast one example, the base plate 30 can be configured to receive atleast one locking screw cap, such as to fix the positioning of thelocking screw 34 within the base plate 30.

The humeral liner 16 can define a split curvature bearing surface 36 ona face of the humeral liner 16 and can include a mounting shank 38 suchas extending from an opposite face of the humeral liner 16. The mountingshank 38 can be received within the port 26 of the attachment head 20,such as to mount the humeral liner 26 to the humeral implant 12. In atleast one example, the split curvature bearing surface 36 can comprise abiocompatible deformable material, such as including, but not limited topolyethylene. The deformable material can facilitate wearing in orbedding of the split curvature bearing surface 36 such as duringprolonged use to improve the fit of the resulting shoulder joint. Thedeformable material can also be configured to deform or deflect throughapplied force from the glenosphere 28 such as to further improve the fitbetween the glenosphere 28 and the split curvature bearing surface 26.In at least one example, the mounting shank 38 can comprise a more rigidmaterial to facilitate improved engagement of the humeral liner 16 tothe attachment head 20.

The spacer 18 can include a port 40 on one face and a mounting shank 42on an opposing face. The port 40 can be configured to receive themounting shank 38 of the humeral liner 16 or the mounting shank 42 ofanother spacer 18 to create a spacer liner stack. The mounting shank 42of the bottommost spacer 18 can be inserted into the port 26 of theattachment head 20, such as to couple the spacer liner stack to theattachment head 20.

A method for implementing the reverse shoulder implant system 10 caninclude preparing the humerus and the glenoid socket of the scapula;mounting the humeral implant to the humerus and the glenoid implant tothe glenoid socket, and slidably engaging the glenosphere 28 to thesplit curvature bearing surface 36. In at least one example, theglenosphere 28 can wear in or bed the split curvature bearing surface 36through continued use of the shoulder joint.

The humerus can be prepared by resecting at least a portion of thehumeral head to expose the medullary cavity of the humerus. In at leastone example, the humeral head region can be resected to provide at leastone generally planar surface for cooperating with the attachment head 20of the humeral implant 12. The glenosphere 28 can be prepared byresecting damaged portions of the scapula adjacent to the glenoidsocket. In at least one example, the scapula can be shaped to provide anengagement surface for receiving the base plate 30 and the lockingscrews 34.

The humeral implant 12 can be mounted by inserting the humeral stem 22into the medullary cavity of the humerus. The humeral stem 22 can becemented within the medullary cavity or retained within the humerus byfriction. In at least one example, the attachment head 20 can have atextured surface 44 for improving engagement of the attachment head 20to the humerus. In certain examples, the textured surface can compriseTRABECULAR METAL®. The attachment head 20 can be positioned within thehumerus such that the planar surface 24 substantially aligns with theplanar or generally planar surfaces of the humerus.

The attachment head 20 can be angled relative to the longitudinal axisof the humeral stem 22, such as to orient the planar surface 24generally toward the glenoid socket when the humeral stem 22 is insertedinto the medullary cavity. The humeral liner 16 can be coupled to theattachment head 20 either directly or stacked with a spacer 18 such thatthe split curvature planar surface 36 is oriented toward the glenoidsocket and at the proper distance.

The base plate 30 can be coupled to the prepared glenoid socket byinserting the locking screws 34 through the base plate 30 and into thescapula. Locking screw caps can be attached, such as to inhibit orprevent adjustment of the locking screws 34 to fix the orientation ofthe base plate 30 within the glenoid socket. In at least one example,the space provided by the surrounding scapula can be evaluated todetermine the appropriate diameter glenosphere 28 for the provided spaceand joint angle. The selected glenosphere 28 can be coupled to the baseplate 30 such that the glenosphere 28 is oriented toward the splitcurvature planar surface 36.

The humerus can be manipulated to contact the glenosphere 28 with thesplit curvature planar surface 36. The deltoid muscle can maintain theglenosphere 28 with the split curvature planar surface 36.

As depicted in FIG. 2, the split curvature planar surface 36 can includea plurality of curvature regions 46. As depicted, the split curvatureplanar surface 36 includes a single split and two curvature regions 46.In certain examples, the split curvature planar surface 36 can includemultiple splits and a plurality of curvature regions 46. In at least oneexample, the plurality of curvature regions 46 can be arrangedconcentrically about a central apex 48 defined by the split curvaturebearing surface 36. In at least one example, one or more of thecurvature regions 46 can be offset from the central apex 48 or centeredon an axis offset from the central apex 48. The split curvature bearingsurface 36 can include at least a first curvature region 46A and asecond curvature region 46B. The first curvature region 46A can have afirst curvature α defined by a first radius R1 extending from a firstfocal point F1. Similarly, the second curvature region 46B can have asecond curvature β defined by a second radius R2 extending from a secondfocal point F2. The second curvature β can be the same as or differentthan the first curvature α. The first focal point F1 and the secondfocal point F2 can be positioned to intersect a center axis 54intersecting the central apex 48 of the split curvature bearing surface36. In at least one example, the first focal point F1 can be positionedcloser to the central apex 48 than the second focal point F2.

In at least one example, the difference between the first radius R1 andthe second radius R2 can be determined such as to reduce or minimize thedifference between the first curvature α and the second curvature β.This arrangement can reduce the likelihood of a significant mismatchbetween the diameter of the glenosphere 28 and the curvature of thefirst or second curvature region 46A, 46B. In an example, the differencebetween the first radius R1 and the second radius R2 can be less thanabout 30%. In at least one example, the difference between the firstradius R1 and the second radius R2 can be less than about 25%. In atleast one example, the difference between the first radius R1 and thesecond radius R2 can be less than about 20%.

As depicted in FIG. 3, the engagement of a glenosphere 28 having a firstdiameter that corresponds to the first curvature α slidably engages thefirst curvature region 46A. In at least one example, the second radiusR2 can be greater than the first radius R1 such that the secondcurvature R is less than the first curvature α. In this arrangement,radial gaps 50 can be created between the curved exterior face 32 of theglenosphere 28 and the second curvature region 46B. In at least oneexample, the surface area of the first curvature region 46A can providesufficient depth for the first curvature region 46A to inhibit orprevent from the glenosphere 28 from tracking within the gaps 50. Duringwearing in or bedding, the glenosphere 28 can wear, deform or deflectthe first curvature region 46A such as to further improve seating of theglenosphere 28 within the split curvature bearing surface 36.

As depicted in FIG. 4, the engagement of a glenosphere 28 having asecond diameter that corresponds to the second curvature 3 slidablyengages the second curvature region 46B. While the second radius R2 canbe greater than the first radius R1, an axial gap 52 is created betweenthe curved exterior face 32 of the glenosphere 28 and the firstcurvature region 46A. In at least one example, the surface area of thefirst curvature region 46A is sufficiently small such that theglenosphere 28 cannot track within the axial gap 52. During wearing inor bedding, the glenosphere 28 can wear, deform or deflect the interfacebetween the first curvature region 46A and/or the second curvatureregion 46B such that the first curvature α approximates the secondcurvature β, such as to improve seating of the glenosphere 28 within thesplit curvature bearing surface 36.

Various Notes & Examples

Example 1 can include subject matter, such as a reverse shoulderreplacement system 10, comprising: a humeral liner 16 defining a splitcurvature bearing surface 36. The split curvature bearing surface 36 caninclude a plurality of curvature regions 46 including at least: a firstcurvature region 46A having a first curvature α and a second curvatureregion 46B having a second curvature β.

Example 2 can include, or can optionally be combined with the subjectmatter of Example 1, to optionally include that the first curvature αcan be defined by a first radius R1 extending from a first focal pointF1 and that the second curvature β can be defined by a second radius R2extending from a second focal point F2.

Example 3 can include, or can optionally be combined with the subjectmatter of Example 1, to optionally include that the first radius R1 isshorter than the second radius R2 such that the second curvature β isshallower than the first curvature α.

Example 4 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 2 or 3 to optionallyinclude that the first radius R1 is at least about 75% of the secondradius R2.

Example 5 can include, or can optionally be combined with the subjectmatter of one or any of the preceding Examples to optionally includethat the first focal point F1 is a first distance from an apex 48 of thesplit curvature bearing surface 36 and the second focal point F2 is asecond distance from the apex 48. The second distance can be greaterthan the first distance.

Example 6 can include, or can optionally be combined with the subjectmatter of one or any of the preceding Examples to optionally includethat the plurality of curvature regions 46 can be arrangedconcentrically such that the second curvature region 46B extends aroundthe first curvature region 46A.

Example 7 can include, or can optionally be combined with the subjectmatter of one or any of the preceding Examples to optionally includethat the humeral liner 16 comprises a biocompatible deformable material.

Example 8 can include, or can optionally be combined with the subjectmatter of Example 7, to optionally include that the biocompatibledeformable material comprises polyethylene.

Example 9 can include, or can optionally be combined with the subjectmatter of one or any of the preceding Examples to optionally including ahumeral implant 12 having a humeral stem 22 insertable into a humerus.The humeral liner 16 can be positioned on an end of the humeral stem.The combination can also include a glenoid implant 14 including aglenosphere 32 and a base plate 30 for receiving at least one fastener34 for mounting the glenoid implant 14 to a scapula.

Example 10 can include, or can optionally be combined with the subjectmatter of Example 9, to optionally include a spacer 18 positionablebetween the humeral liner 16 and the humeral stem 22.

Example 11 can include subject matter, such as a method that can includeinserting a stem 22 of a humeral implant 12 into a humerus and mountinga humeral liner 16 to an end of the stem 22. The humeral liner 16 candefine a split curvature bearing surface 36 including a plurality ofcurvature regions 46. The curvature regions 46 can include at least: afirst curvature region 46A having a first curvature α and a secondcurvature region 46B having a second curvature β. The method can alsoinclude mounting a glenoid implant 14 to a glenoid region of a scapulawhere the glenoid implant 14 includes a glenosphere 32, and positioningthe humeral implant 12 such that at least one of the curvature regions46A, 46B operably engages the glenosphere 32 of the glenoid implant 14.

Example 12 can include, or can optionally be combined with the subjectmatter of Example 11, to optionally include that the first curvature αcan be defined by a first radius R1 extending from a first focal pointF1 and that the second curvature β can be defined by a second radius R2extending from a second focal point F2.

Example 13 can include, or can optionally be combined with the subjectmatter of Example 12, to optionally include that the first radius R1 isshorter than the second radius R2 such that the second curvature β isshallower than the first curvature α.

Example 14 can include, or can optionally be combined with the subjectmatter of one or any combination of Examples 12 or 13 to optionallyinclude that the first radius R1 is at least about 75% of the secondradius R2.

Example 15 can include, or can optionally be combined with the subjectmatter of one or any of preceding Examples 11-14 to optionally includethat the first focal point F1 is a first distance from an apex 48 of thesplit curvature bearing surface 36 and the second focal point F2 is asecond distance from the apex 48. The second distance can be greaterthan the first distance.

Example 16 can include, or can optionally be combined with the subjectmatter of one or any of preceding Examples 11-15 to optionally includethat the plurality of curvature regions 46 can be arrangedconcentrically such that the second curvature region 46B extends aroundthe first curvature region 46A.

Example 17 can include, or can optionally be combined with the subjectmatter of one or any of preceding Examples 11-16 to optionally includethat the humeral liner 16 comprises a biocompatible deformable material.

Example 18 can include, or can optionally be combined with the subjectmatter of Example 17, to optionally include that the biocompatibledeformable material comprises polyethylene.

Example 19 can include, or can optionally be combined with the subjectmatter of one or any of preceding Examples 11-18 to optionally includeresecting at least a portion of the humerus to provide a humeralmounting surface for receiving the humeral implant 12; and resecting atleast a portion of the scapula to provide a glenoid mounting surface forreceiving the glenoid implant 14.

Example 20 can include, or can optionally be combined with the subjectmatter of one or any of preceding Examples 11-18 to optionally includepositioning a spacer 18 between the humeral liner 16 and the humeralstem 12.

Each of these non-limiting examples can stand on its own or can becombined in any permutation or combination with any one or more of theother examples.

The above-detailed description includes references to the accompanyingdrawings, which form a part of the detailed description. The drawingsshow, by way of illustration, specific embodiments in which the presentsubject matter can be practiced. These embodiments are also referred toherein as “examples.” Such examples can include elements in addition tothose shown or described. However, the present inventors alsocontemplate examples in which only those elements shown or described areprovided. Moreover, the present inventors also contemplate examplesusing any combination or permutation of those elements shown ordescribed (or one or more aspects thereof), either with respect to aparticular example (or one or more aspects thereof), or with respect toother examples (or one or more aspects thereof) shown or describedherein.

In the event of inconsistent usages between this document and anydocuments so incorporated by reference, the usage in this documentcontrols.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of“at least one” or “one or more.” In this document,the term “or” is used to refer to a nonexclusive or, such that “A or B”includes “A but not B,” “B but not A,” and “A and B.” unless otherwiseindicated. In this document, the terms “including” and “in which” areused as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, device,article, composition, formulation, or process that includes elements inaddition to those listed after such a term in a claim are still deemedto fall within the scope of that claim. Moreover, in the followingclaims, the terms “first,” “second,” and “third,” etc. are used merelyas labels, and are not intended to impose numerical requirements ontheir objects.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) may be used in combination with each other. Otherembodiments can be used, such as by one of ordinary skill in the artupon reviewing the above description. The Abstract is provided to complywith 37 C.F.R. § 1.72(b), to allow the reader to quickly ascertain thenature of the technical disclosure. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims. Also, in the above Detailed Description,various features may be grouped together to streamline the disclosure.This should not be interpreted as intending that an unclaimed disclosedfeature is essential to any claim. Rather, inventive subject matter maylie in less than all features of a particular disclosed embodiment.Thus, the following claims are hereby incorporated into the DetailedDescription as examples or embodiments, with each claim standing on itsown as a separate embodiment, and it is contemplated that suchembodiments can be combined with each other in various combinations orpermutations. The scope of the present subject matter should bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled.

1-11. (canceled)
 11. A method for reverse replacement of a shoulderjoint, comprising: inserting a stem of a humeral implant into a humerus;mounting a humeral liner to an end of the stem, wherein the humeralliner defines a split curvature bearing surface including a plurality ofcurvature regions including at least: a first curvature region having afirst curvature, and a second curvature region having a secondcurvature; mounting a glenoid implant to a glenoid region of a scapula,the glenoid implant including a glenosphere; and positioning the humeralimplant such that at least one of the curvature regions operably engagesthe glenosphere of the glenoid implant.
 12. The method of claim 11,wherein the first curvature is defined by a first radius extending froma first focal point positioned a first distance from an apex; whereinthe second curvature is defined by a second radius extending from asecond focal point positioned a second distance from the apex.
 13. Themethod of claim 12, wherein the first radius is shorter than the secondradius such that the second curvature is shallower than the firstcurvature.
 14. The method of claim 12, wherein the first radius is atleast about 75% of the second radius.
 15. The method of claim 11,wherein the first focal point is a first distance from an apex of thesplit curvature bearing surface and the second focal point is a seconddistance from the apex; wherein the second distance is greater than thefirst distance.
 16. The method of claim 11, wherein the plurality ofcurvature regions are arranged concentrically such that the secondcurvature region extends around the first curvature region.
 17. Themethod of claim 11, wherein the humeral liner comprises a biocompatibledeformable material.
 18. The method of claim 17, wherein thebiocompatible deformable material comprises polyethylene.
 19. The methodof claim 11, further comprising: resecting at least a portion of thehumerus to provide a humeral mounting surface for receiving the humeralimplant; and resecting at least a portion of the scapula to provide aglenoid mounting surface for receiving the glenoid implant.
 20. Themethod of claim 11, further comprising: positioning a spacer between thehumeral liner and the humeral stem.
 21. A method for reverse replacementof a shoulder joint, comprising: mounting a humeral implant to ahumerus; securing a humeral liner to the humeral implant, wherein thehumeral liner defines a split curvature bearing surface including aplurality of curvature regions including at least: a first curvatureregion having a first curvature, and a second curvature region having asecond curvature different than the first curvature; selecting a glenoidimplant from a plurality of glenoid implants including at least oneglenoid implant having a first curved exterior surface that matches thefirst curvature of the first curvature region and at least one glenoidimplant having a second curved exterior surface that matches the secondcurvature of the second curvature region; and mounting the selectedglenoid implant to a glenoid region of a scapula.
 22. The method ofclaim 21, further comprising: positioning the selected glenoid implantrelative to the humeral liner such that the selected glenoid implantoperably engages either the first curvature region or the secondcurvature region.
 23. The method of claim 22, further comprising:inserting a spacer between the humeral liner and a stem of the humeralimplant.
 24. The method of claim 21, wherein the plurality of curvatureregions are arranged concentrically such that the second curvatureregion extends around the first curvature region.
 25. The method ofclaim 21, wherein the first curvature is defined by a first radiusextending from a first focal point, and wherein the second curvature isdefined by a second radius extending from a second focal point.
 26. Themethod of claim 25, wherein the first radius is shorter than the secondradius such that the second curvature is shallower than the firstcurvature.
 27. A method for reverse replacement of a shoulder joint,comprising: mounting a humeral implant to a humerus; securing a humeralliner to the humeral implant, wherein the humeral liner defines a splitcurvature bearing surface including a plurality of curvature regionsincluding at least: a first curvature region defined by a firstcurvature, and a second curvature region defined by a second curvaturedifferent than the first curvature; selecting a glenoid implant from aplurality of glenoid implants including at least one glenoid implanthaving a first glenoid bearing surface defined by a first diameter thatcorresponds to the first curvature and at least one glenoid implanthaving a second glenoid bearing surface defined by a second diameterthat corresponds to the second curvature; and mounting the selectedglenoid implant to a glenoid region of a scapula.
 28. The method ofclaim 27, further comprising: positioning the selected glenoid implantrelative to the humeral liner such that the selected glenoid implantoperably engages either the first curvature region or the secondcurvature region.
 29. The method of claim 27, further comprising:preparing the humerus for receipt of the humeral implant; and preparingthe scapula for receipt of the selected glenoid implant.
 30. The methodof claim 27, wherein the first curvature region is defined by a firstradius that extends from a first focal point and the second curvatureregion is defined by a second radius that extends from a second focalpoint, the first and second focal points disposed along a longitudinalaxis that intersects a central apex of the humeral liner.